The present invention relates to a sustained release preparation of labetalol. Specifically, it relates to an oral dosage form which provides a release period suitable for single daily dosing which exhibits good bioavailability.
Labetalol hydrochloride, 5-[1-hydroxy-2-(1-methyl-3-phenylpropyl)aminoethyl]salicylamide HC1, is an adrenergic receptor blocking agent that has both selective alpha.sub.1 - and non-selective beta-adrenergic receptor blocking action. This drug is effective in the management of hypertension. The conventional dosage form marketed is intended for twice daily administration. A key factor in the management of hypertension is patient compliance and one approach to improving patient compliance is to reduce the number of times the patient must take the medication during a given period.
Labetalol hydrochloride, though appreciably soluble in lower and higher pH solutions, shows minimum solubility between pH 6 to 10. Consequently although labetalol hydrochloride may be soluble and available for absorption in gastric pHs, it may not be available for absorption at intestinal pHs due to precipitation of labetalol hydrochloride in this pH range.
U.S. Pat. Nos. 4,012,444 and 4,066,755 disclose labetalol hydrochloride, its preparation and uses in the treatment of hypertension.